Total mercury monitor

ABSTRACT

APPARATUS AND METHOD ARE PROVIDED FOR ANALYZING LIQUID STREAM FOR THEIR CONTENT OF MERCURY INCLUDING ELEMENTAL MERCURY, IONIC MERCURY AND UNDISSOCIATED MERCURY COMPOUNDS SUCH AS PHENYL MERCURY AND METHYL MERCURY. THE SAMPLE IS AUTOMATICALLY MEASURED AND FIRST TREATED WITH AN ACIDIC METAL SALT REAGENT CONTAINING AN OXIDANT FOR OXIDIZING ELEMENTARY MERCURY IN THE SAMPLE TO IONIC MERCURY AND THEN WITH HYDRAZINE TO FORMA SUITABLE CATALYTIC COLLID. ELEMENTARY MERCURY IS THEN FORMED BY THE ACTION OF HYDRAZINE AND THE CATALYTIC COLLOID ON THE IONIC AND COMBINED MERCURY AND IS TRANSFERRED TO A PHOTOMETRIC DETECTOR. THE RESULTS ARE INDICATED AND/OR RECORDED AUTOMATICALLY, ACCURATELY AND RAPIDLY. THE AP-   PARATUS AND METHOD ARE ESPECIALLY USEFUL IN THE CONTROL OF MERCURY CONTAMINATION IN THE ENVIRONMENT AND ALSO FOR MONITORING CHEMICAL PROCESS STREAMS.

Juky 3@, mm a. A. CAPUANO TOTAL MERCURY MONITOR Filed May 17, 1972SAMPLE CARR/ER L/OU/D IN 6A5 W 5/ /& /Z\

METAL SALT SOLUTION S TORAGE 2 Sheets-Sheet l H VDRAZ/NE REA GENTSTORAGE r75 VACUUM SAMPLE L/QU/D OUT PROGRAMMER DE TE C TOR RECORDERIND/CA TOR Y n. A. CAPUANO TOTAL MERCURY MONITOR Filed May 1'7, 1972 2Sheets-Sheet 2 3,826,614 TOTALMERCURY MONITOR Italo A. Capuano, Orange,Conn., assignor to Ionics, incorporated, Watertown, Mass.Continuation-impart of applications Ser. No. 75,927, Sept. 28, 1970, nowPatent No. 3,713,776, and Ser. No. 115,175, Feb. 16, 1971, now PatentNo. 3,704,097. This application May 17, 1972, Ser. No. 254,251

Int. Cl. Glln 21/26, 31/10, 33/18 US. Cl. 23-230 R 14 Claims ABSTRACT OFTHE DISCLOSURE Apparatus and method are provided, for analyzing liquidstreams for their content of mercury including elemental mercury, ionicmercury and undissociated mercury compounds such as phenyl mercury andmethyl mercury. The sample is automatically measured and first treatedwith an acidic metal salt reagent containing an oxidant for oxidizingelementary mercury in the sample to ionic mercury and then withhydrazine to form a suitable catalytic colloid. Elementary mercury isthen formed by the action of hydrazine and the catalytic colloid on theionic and combined mercury and is transferred to a photometric detector.The results are indicated and/or recorded automatically, accurately andrapidly. The apparatus and method are especially useful in the controlof mercury contamination in the environment and also for monitoringchemical process streams.

This invention relates to a method and apparatus for applications Ser.No. 75,927 filed Sept. 28, 1970, now US. Pat. No. 3,713,776, issued Jan.30, 1973 and Ser. No. 115,175, filed Feb. 16, 1971, now US. Pat. No.3,704,- 097. issued Nov. 28, 1972.

This invention relates to a method and apparatus for continuous,automatic analysis of a liquid for its content of mercury. The liquidsare suitably aqueous, either a flowing stream or in discrete portions.The mercury is suitably in the formof elemental mercury, ionic mercuryof any kind and undissociated mercury in organic compounds, for example,methyl mercury and phenyl mercury. All of these are rapidly reduced byaqueous hydrazine under the catalytic action of a colloidal metal oxidecatalyst. The colloidal contact catalyst is suitably a metal oxideformed by the action of hydrazine on a metal salt which is effectivewith hydrazine to convert ionic or undissociated mercury to metallicmercury. The oxides here referred to may be more or less hydrated oxidesor hydroxides. The colloidal catalysts prepared as described herein donot appear to be the metal sols described by Weiser, Inorganic ColloidChemistry, Vol. 1, p. 138 (1933). It is important that the colloid isnot a metal which amalgamates with mercury, for example, copper orsilver. Colloidal silver, formed by reaction of hydrazine with asolution of silver salt, amalgamates with mercury and consequentlyinterferes with the mercury determination by the apparatus and method ofthis invention.

Aqueous liquids have previously been analyzed manually for ionic andorganic mercury by reducing with hydrazine and colloidal copper metalwith subsequent oxidation of the solution containing the resultingcopper amalgam with sulfuric acid and potassium permanganate reagent andfinally titrating with dithizone. See Nobel et al., Clinical Chemistry,4, No. 2, pp. 150-458 (1958).

Also, ionic mercury in liquids has been manually analyzed by reductionwith acidic stannous chloride, vaporizing the mercury and measuringphotometrically the intensity of its 2537 Angstrom units spectral line.See Dill,

ted States Paten 3,826,614 Patented July 30, 1974 ice US. Atomic EnergyCommission, Report Y-l572, issued Mar. 28, 1967 and Rathje, AmericanHygiene Association Journal 30, 126-132 (1969).

The method and apparatus of this invention is useful for determiningautomatically the mercury in aqueous streams that may be discharged tounderground storage or to surface drainage. Mercury contaminated streamsoriginate in locations where mercury or its compounds are used inmanufacturing various products, for example, in chlor-alkali plantsoperating mercury cells, felt manufacturing plants, plants formanufacturing mercury-containing pesticides, instruments, lamps,batteries and medicinals.

A major difficulty in controlling mercury contamination of theenvironment in industrial areas has been the lack of automatic methodsand apparatus capable of analyzing for mercury quickly, accurately andcontinuously. Some proposed methods and apparatus are not suited for usein contaminated environments where, for example, chlorine gas adverselyaifects the function and structure of the apparatus or where othercontaminants lead to false results. When mercury, as a contaminant, ispresent as the element or as salts, for example, as chloride salts,methods and apparatus employing pyrolytic reduction do not accuratelyrespond to such mercury chloride salts. Because mercury is frequentlypresent in various forms, fluid samples cannot give accurate analyseswhen passed directly into many of the devices available for mercuryanalysis. This difficulty is overcome according to the present inventionby converting the various forms of mercury to elementary mercurychemically and measuring its amount using instruments highly sensitiveto the vapor of elementary mercury. The method and apparatus of thepresent invention are useful and accurate or analysis of samplescontaining other contaminants, particularly elemental or availablechlorine.

The method and apparatus of this invention removes and measures a finitesample of the liquid to be analyzed and processes the sampleautomatically to the finally indicated and/or recorded result. Thesample is suitably removed and measured from a supply which may bemoving or quiescent, i.e., it may be a flowing stream or a stationarybody of liquid brought to the place of analysis. It is, however, afeature of the apparatus of the present invention, that it is portableand is suitably transported to the place Where the liquid to be analyzedis located. Advan'tageously, the sample points used in conjunction withthe method and apparatus of this invention are lo cated sufficientlyupstream of a disposal point to permit remedial steps to be taken tocorrect contamination before discharge of the stream under test when themethod of this invention indicates the necessity of such action.

Mercury in the fluids analyzed is determined accurately and quickly bythe method and apparatus of this invention when the mercury is presentas one or more of the entities, Hg, Hg Hg+ or undissociated mercuryorganic compounds, for example, methyl mercury and phenyl mercury. Theentity Hg represents elemental mercury. It is sometimes present asliquid mercury usually dispersed or emulsified as droplets in aqueousliquids. The entity Hg+ represents monovalent ionic mercury usuallypresent in aqueous liquids as dissolved or suspended salts of mercurousmercury. The entity Hg+ represents divalent ionic mercury usuallypresent in aqueous liquids as dissolved or suspended salts of mercuricmercury. Undissociated mercury organic compounds are usually dissolvedor suspended in aqueous liquids.

This application is directed to a modification of the method andapparatus disclosed and claimed in the parent application and isparticularly advantageous Where the sample for analysis containselementary mercury in the form of particles of various sizes. Largerparticles vaporize less rapidly than smaller particles in thevaporization step of the process. In the present modification, thisvariation is avoided by first oxidizing elementary mercury in the sampleto ionic mercury using a suitable oxidant. Subsequentreduction toelementary mercury by hydrazine in the presence of colloidal metal oxidecatalyst produces particles of elementary mercury of such uniform sizethat vaporization is substantially complete at a uniform rate.

Included in the metal salt reagent solution is a minor amount of asoluble oxidant for the oxidation of elementary mercury. Suitableoxidants are those known to effectively oxidize elementary to ionicmercury, for example, permanganates, peroxides, nitric acid andpersulfates. Minor amounts of mineral acid are also included in themetal salt reagent solution to enhance the action of the oxidant.Sulfuric acid in conjunction with persulfates or permanganates isespecially suitable. Nitric acid alone serves advantageously both asoxidant and acidifying agent. The acid has the further function ininsuring that elementary mercury is not adherent to the walls of thetransfer lines and valves and is quantitatively transferred to thescrubbing and vaporizing zone.

As oxidants, alkali metal permanganates, peroxides and persulfates aresuitable. Potassium persulfate is most readily available and preferred.

Mercury thus converted to ionic form and mercury present in organiccompounds is reduced to the metallic state by aqueous hydrazine in thepresence of a colloidal titanium oxide, nickel oxide or copper oxidecontact catalyst and analyzed according to the method of this invention.

I The method and apparatus of this invention are also suitably used tomeasure the elfectiveness of operation of mercury-removing ormercury-introducing machines, processes and systems by measuring themercury content of input and output streams.

The method of the present invention automatically monitors a liquid forthe total content of mercury when it is present therein as at least oneof the entities, Hg Hg' Hg+ and undissociated mercury compounds byprogramming and mechanically performing successively and repetitivelythe operation of:

(a) providing aqueous hydrazine reagent in a first reagent storage zoneand an acidic metal salt solution containing dissolved oxidant forelementary mercury in a second reagent storage zone;

(b) removing from said reagent storage zone a hydrazine reagent portionof predetermined amount and transferring said hydrazine reagent portionto a scrubbing zone;

(c) scrubbing said hydrazine reagent portion in said scrubbing zone witha gaseous carrier;

(d) separating said gaseous carrier from the resulting aqueous mixturein said scrubbing zone;

(e) transferring said carrier to a pyrolyzing zone and pyrolyzing saidcarrier and admixed components to remove interfering material from saidgaseous carrier;

(f) transferring said carrier to a measuring zone and automaticallyadjusting the base line reading to zero;

(g) providing a fluid to be monitored for mercury therein;

(h) removing from said fluid a sample of predetermined amount in asample measuring zone;

(i) removing from said second reagent storage zone a metal salt andoxidant reagent portion of predetermined amount and mixing said metalsalt and oxidant reagent portion with said sample in said samplemeasuring zone;

(1 transferring the thus measured and treated sample to said scrubbingzone;

(k) scrubbing the resulting mixture of said sample with said aqueousmixture in said scrubbing zone with said carrier;

(1) separating said gaseous carrier from the resulting aqueous liquid insaid scrubbing zone;

(m) transferring said carrier to said pyrolyzing zone and pyrolyzingsaid carrier and admixed components to remove interfering material fromsaid gaseous carrier;

(n) transferring said carrier to said measuring zone and photometricallymeasuring the quantity of mercury in said carrier;

(0) indicating the quantity of mercury in said carrier relative to thepredetermined amount of said sample.

Apparatus suitable for use in carrying out the process of the presentinvention has means including: 1

(a) programming means for mechanically activating and deactivatingsuccessively and repetitively;-

(b) means for removing from a fluid a sample of predetermined amount ina sample measuring zone and means for transferring the thus measuredsample to a scrubbing zone;

(c) means for transferring a predetermined amount of acidic metal saltreagent containing dissolved oxidant from a storage zone therefor tosaid sample measuring zone;

(d) means for circulating aqueous hydrazine reagent cyclically from areagent storage zone through a reagent valve and through a reagentmeasuring zone and return to said reagent storage zone;

(e) means for removing from said circulating hydrazine reagent apredetermined amount of said hydrazine reagent and for transferring saidamount of hydrazine reagent to said scrubbing zone;

(f) means for scrubbing the mixture in said scrubbing zone with agaseous carrier;

(g) means for separating said gaseous carrier containing mercury vaporfrom the resulting aqueous liquid in said scrubbing zone;

(h) means for transferring said carrier containing mercury vapor to apyrolyzing zone to remove interfering materials from said gaseouscarrier;

(i) means for transferring the resulting purified gaseous carriercontaining mercury vapor to a measuring zone;

(j) photometric means for measuring the quantity of mercury in saidcarrier;

(k) means for indicating the quantity of mercury in said carrierrelative to the predetermined amount of said sample.

CALIBRATION Suitably, mercury-free gas carrier and aqueous liquidstandards containing known amounts of mercury are introduced andanalyzed to calibrate the system. Care must be exercised to avoid theintroduction of carrier gas containing unknown or variable amounts ofmercury which would affect the determination. Mercury-free carrier gasis suitably provided from a source of pure, compressed gas,advantageously from a cylinder of compressed gas. Alternatively, air issuitably brought to the apparatus from a remote uncontaminated location.The inert gaseous carrier is suitably air, nitrogen, hydrogen, helium,argon or other gases inert to aqueous hydrazine and catalyst andnon-absorbing in the ultraviolet region.

Suitable and preferred aqueous hydrazine reagent is a 10 percentsolution. However, the composition of the aqueous hydrazine reagent isnot critical between 2 to 35 percent. The aqueous metal salt solution issuitably about 0.5 percent; however, its concentration is not criticaland may be suitably between 0.05 and 5 percent. Suitable metal salts arereduced by hydrazine to colloidal metal oxides effective to convertionic or undissolved mercury to metallic mercury. Suitable oxides arenonbasic and include copper, nickel and titanium oxides. Preferred saltsare the halides, sulfates and nitrates of cupric copper, nickel andtitanous titanium.

The acidic aqueous metal salt solution also contains an oxidant, forexample, a persulfate, suitably an alkali metal persulfate andpreferably potassium persulfate suitably in an amount of about 3percent; however, the concentration of the oxidant is not critical andmay suitably be between 0.05 and 5 percent. The aqueous metal saltsolution also contains a minor amount of mineral acid, suitably sulfuricor nitric acid, in an amount of about 2 percent; it is also not criticaland may suitably be between 0.05 and 5 percent.

It is important that the mercury content, if any, of the metal saltreagent, also containing the oxidant and acid, be predetermined and thata suitable correction factor be applied to the measured content ofmercury in the sample. The predetermination is suitably performed byanalysis using the method and apparatus here disclosed and claimed or byany suitable. preliminary manual analysis. Preferably, by the use ofpure reagents, the mercury content of the reagent is negligible.

At start-up, a measured amount of aqueous hydrazine reagent istransferred to a suitable scrubber. Mercuryfree carrier is bubbledthrough the liquid at a constant rate and is transferred through thepyrolyzer to the detectorQThe detector is then automatically zeroed by aservornechanism under the control of the programmer. The liquid samplecontaining mercury is then introduced and analyzed.

ANALYSIS OF SAMPLE The liquid sample suitably flows continuously throughthe sampling and measuring means. When the detector has beenautomatically zeroed, using the aqueous hydrazine reagent as describedabove, a measured sample is removed from the flowing stream in thesample measuring zone, a predetermined amount of metal salt solutioncontaining oxidant is injected into the sample in the sample measuringzone where elementary mercury is oxidized to ionic mercury. The thusmeasured and treated sample is then transferred to the scrubber andmixed with the hydrazine reagent in the scrubber. Mercury in any form inthe sample is converted substantially instantaneously to-elementalmercury. The stream of carrier gas transporting the mercury vapor passesthrough a high temperature pyrolyzer where it is heated to about 500 to1200 C. to remove possible interfering materials vaporized from thesample and then passes through a photometric analyzer and out, suitablyunder the influence of reduced pressure. The analysis is indicated bythe detector andis suitably recorded. A plurality of liquid samplepoints are suitably selected serially by programmer and analyzed. Eachanalysis requires about 6 minutes and each analysis uses fresh portionsof aqueous hydrazine reagent and metal salt solution.

APPARATUS The measurement'and flow of sample, carrier gas and reagentare directed by any suitable programmer-operated valve having a suitablenumber of ports. One commercially available valve suitable for use assample valve andreagent valve in the apparatus of this invention is theLG-6 sliding insert valve No. W 122437 of Beckman Instruments, Inc., butany other suitable valve will serve. Advantageously, such valves arefabricated of Kel-F or. other suitable plastic parts and the ports andother fluid-carrying passages are lined with plastic. These valvessuitably have a plurality of ports sufficient to perform the functionsdesired and may be from 2 to 10. The 6-port valves are suitable forsample and reagent valves in the apparatus of the present invention.Other valves in the system usually have 2 or 3 ports.

An injector pump capable of transferring a predetermined portion ofmetal salt solution into the system is used but any other suitable meanscan be used for this purpose. A high temperature furnace with a suitabletube is used to remove interfering materials, particularly organics,from the vapor. The tube is advantageously, though not necessarily, atube of silica.

A terminal vacuum is generated and applied to induce the flow of gaseouscarrier through the system. The vacuum generator is under control of theprogrammer and is activated when analyses begin and continues to operateuntil no further analyses are to be made. Suitably an exit pressure of740:10 mm. is maintained when the apparatus and inlet lines are at sealevel atmospheric pressure and generally at pressures of about 10 to 30mm. below inlet pressures. Positive pressure instead of vacuum can alsobe employed to move the gaseous carrier through the system.

DETECTOR One suitable detector is the DuPont 400 photometric analyzerwhich is suitable for use with standard millivolt, self-balancingrecorders having unbalanced impedance over 10,000 ohms. Analyzer outputimpedance is up to 20,000 ohms. Power at 110 volts and 60 Hertz issupplied. A suitable recorder is Leeds and Northup Speedomax H with arange of 0 to 10 millivolts. Other suitable instruments are available.

The preferred detector has an ultraviolet light generator at one endwhich illuminates a one-meter tube through which carrier gas passes.Mercury vapor in the gas absorbs the 2537 Angstrom unit wave length andreduces the intensity of the light at the other end of the tube where aphotocell is located. The current passing through the photocell isinversely proportional to the amount of mercury vapor in the tube.

PROGRAMMER Any suitable programmer is useful in the method and apparatusof this invention. Advantageously, the programmer incorporates selectormeans whereby any of a plurality of sample sources are activated toprovide a sample for analysis according to the method of this invention.Suitably the programmer is a timer adapted to close and open circuits insequence for selected periods of time, to activate and shut down thevacuum terminally applied to the system, to activate and shut down theaqueous reagent and metal salt solution pumps, to open and close valveswhich permit the flow of measured amounts of reagents, sample and, whendesired, inert diluent gas through the system and to activate and shutdown the detector and recorder-indicator. Programmers are commerciallyavailable which are suitably adjustable to pro vide the desired sequenceof operations. One suitable programmer is No. 520 manufactured byBeckman Instruments, Inc. but other commercial devices are suitable.

DRAWINGS FIG. 1 illustrates a system of the invention capable ofanalyzing liquids. FIG. 1 shows chemical flow lines but omits electricallines shown in FIG. 2.

In FIGS. 1 and 2, line 16 is provided for introducing carrier gas intothe system through valve 49, operated by solenoid 51 under control ofprogrammer 101 via line 112. Suflicient vacuum is applied via line 44 todraw the carrier gas through the entire system. The carrier gas istransferred via line 6 controlled by the pressure regulator consistingof valve 17 and line 18 under the pressure indicated by gage 19 andthrough. valve 32 operated by programmer 101 using line 104 to solenoid33. Sample valve 11 is activated by programmer 101 via line 102 topermit flow of carrier gas from line 16 through line 20 to scrubber 21.

While gaseous carrier is flowing through the system, pump 24 normallycirculates aqueous hydazine reagent from reagent storage 25 to reagentvalve 22 via line 26, through measuring device 29 via lines 28 and 30and back to reagent storage 25 via lines 23 and 27. Programmer 101operates via line to shut down pump 24 and reagent valve 22 is operatedto Withdraw carrier gas from line 31 into line 28. Flow of air in line31 is regulated by valve 34 operated by solenoid 35 under control ofprogrammer 101 via line 105. Carrier gas and the measured quantity ofaqueous hydrazine reagent is transferred via line 36 to scrubber 21.

Simultaneously with the operation of valve 22, as described, injectorpump 10 is activated by programmer 101 via line 111 to admit apredetermined amount of metal salt solution containing oxidant fromstorage 9 via lines 6 and 7 into sample measuring device 14. After asuitable time of 0.1 to 3 minutes or more, the sample contains all themercury in ionic form and is transferred via sample valve 11 and line 20into scrubber 21.

In scrubber 21, the gas is separated from the aqueous portion andtransferred via line 37 to pyrolyzer 50. This transfer is controlled byvalve 39 operated by solenoid 40 programmed by programmer 101 via line106. The pyrolyzed carrier gas passes via line 48 to detector 38. Detector 38 indicates the amount of mercury, if any, in the gaseous carrierand advantageously records the result by means of connectedrecorder-indicator 41. Detector 38 operates on a flow of gas, which isexhausted via line 42 through flowmeter 43' under the influence ofvacuum applied via line 44. By means of the above-described procedure, ablank is established on the reagents and gaseous carrier and thedetector is auto-zeroed. Programmer 101 operates valve 39 to shut 01fthe vacuum and admit air via line 52. Programmer 101 then energisessolenoid 47 via line 107 and opens valve 46, whereby the aqueous mixtureis discharged via line 45 and the system is ready for analysis ofsamples.

In analyzing liquids, gaseous carrier flow is continued through thesystem, aqueous hydrazine reagent is circulated and measured and metalsalt solution is injected as described above. The liquid to be analyzedis introduced via line 12, flows via line 13 through sample measuringdevice 14 and returns via line 15 to sample valve 11 and discharges vialine 12a. Operation of sample valve 11 directs the flow of liquid fromline 12 to line 12a. Valve 11 is operated to cut off a measured sampleof the liquid in measuring device 14 and associated lines, injector pump10 is activated by programmer 101 via line 111 to admit a predeterminedamount of metal salt solution containing oxidant from storage 9 vialines 6 and 7 into sample measuring device 14. After oxidation ofelementary mercury in the sample to ionic mercury, valve 11 is operatedto transfer the measured and thus treated sample via line 10 to scrubber21. Pyrolysis, detection and recording are continued as described above.The analysis, from time of sampling to time of indicating the result,requires about 6 minutes. In preparation for the next analysis, theaqueous liquid in scrubber 21 is discharged via line 45 by the proceduredescribed above. Because the liquid sample is mixed with the aqueoushydrazine reagent and catalyst, each analysis of liquid sample requiresa fresh charge of aqueous hydrazine reagent and of metal salt solution.

Example I A system as shown in FIGS. 1 and 2 was set up using a DuPont400 photometric analyzer with a l-meter cell. Samples of watercontaining 100 p.p.b. (parts per billion) of elemental mercury wereanalyzed as described using air carrier flow of 1.5 liters per minute,10 ml. of water sample, 10 ml. of 10 percent aqueous hydrazine reagentand 0.5 ml. of 0.5 percent aqueous cupric chloride and 2 percent ofsulfuric acid with and without 3 percent of potassium persulfate. Eachanalysis required about 6 min utes. The reactor was calibrated andseveral samples were analyzed using the metal salt solution with andWithout the K 5 oxidant. Four analyses without K S O indicated themercury content of the water samples to be 60, 66, 67 and 54 p.p.b. Withthe K 0 oxidant in the metal salt solution, four analyses showed 99,100, 98 and 100 p.p.b. of mercury compared to the known value of 100p.p.b. of mercury.

Example 11 Using the system shown in FIGS. 1 and 2 and the proceduredescribed in Example I, samples of water containing 60 p.p.b. of methylmercury chloride were analyzed. The metal reagent contained 0.5 percentof cupric chloride, 2 percent of sulfuric acid and 3 percent ofpotassium permanganate. Four analyses showed mercury contents of 62, 63.61 and 61.5 p.p.b. of mercurry.

Example III A system according to FIGS. 1 and 2 for analysis of mercuryusing the procedure described above was employed to analyze varioussamples of mercury sulfide suspended in water and containing parts perbillion of mercury. The metal reagent contained 0.5 percent of cupricchloride, 2 percent nitric acid and 3 percent of potassium permanganate.Four analyses showed mercury contents of 107, 102, 102 and 105.7 p.p.b.of mercury.

What is claimed is:

1. In a method for automatically monitoring a fluid for the content ofmercury present therein by programming and mechanically performingsuccessively and repetitively the operations of: V

(a) providing aqueous hydrazine reagent in a first re agent storage zoneand a metal salt solution in a second reagent storage zone;

(b) removing from said first reagent storage zone a hydrazine reagentportion of predetermined amount and transferring said hydrazine reagentportion to a scrubbing zone;

(0) scrubbing said hydrazine reagent portion in said scrubbing zone witha gaseous carrier;

(d) separating said gaseous carrier from the resulting aqueous mixturein said scrubbing zone;

(e) transferring said carrier to a pyrolyzing zone and pyrolyzing saidcarrier and admixed components 'to remove interfering material from saidgaseous carrier;

(f) transferring said carrier to a measuring zone and automaticallyadjusting the base line reading to zero;

(g) providing a fluid to be monitored for mercury therein;

(h) removing from said fluid a sample of predetermined amount in asample measuring zone;

(i) transferring said sample to said srubbing zone;

(j) scrubbing said sample with said aqueous mixture in said scrubbingzone with said carrier,

(k) separating said gaseous carrier from the resulting aqueous liquid insaid scrubbing zone;

(1) transferring said carrier to said pyrolyzing zone and pyrolyzingsaid carrier and admixed components to remove interfering material fromsaid gaseous carrier;

(m) transferring said carrier to said measuring zone and photometricallymeasuring the quantity of mercury in said carrier;

(11) indicating the quantity of mercury in said carrier relative to thepredetermined amount of said sample,

the improvement which comprises the steps of:

(1) adding a mineral acid to said metal salt solution to form anacidified metal salt in said second reagent storage zone,

(2) dissolving an oxidant for elementary mercury in said acidified metalsalt solution;

(3) transferring from said second reagent storage zone a portion of saidacidified metal salt solution containing said dissolved oxidant to saidsample measuring zone; and

(4) mixing said sample of fluid with said portion in said samplemeasuring zone.

2. The method of claim 1 in which said metal salt is selected from thegroup consisting of the halides, sulfates and nitrates of nickel, cupriccopper and titanous titanium.

3. The method of claim 2 in which said metal salt solution contains from0.05 to 5 percent of said metal salt, from 0.05 to 5 percent of saidmineral acid and from 0.05 to 5 percent of said oxidant.

4. The method of claim 3 in which said oxidant for elementary mercury isan alkali metal compound selected from the group consisting of alkalimetal permanganates, alkali metal peroxides and alkali metalpersulfates.

5. The method of claim 4 in which said alkali metal compound ispotassium persulfate.

6. The method of claim in which said mineral acid is sulfuric acid.

7. The method of claim 1 in which said carrier is heated in saidpyrolyzing zone to a temperature of 500 to 1200 C.

8. The method of claim 1 in which said gaseous carrier 1s arr.

9. The method of claim 1 in which the quantity of mercury vapor in saidcarrier is measured photometrically by radiating said mercury vapor withelectromagnetic energy of wave length 2537 Angstrom units and measuringthe amount of the energy absorbed at said wave length.

10. The method of claim 1 in which the quantity of mercury relative tothe predetermined amount of said sample is additionally recorded.

11. The method of claim 1 in which each of a plurality of fluids aresuccessively treated until the resulting photometric measurement foreach passes a peak value and automatically switching to another sampleof fluid until samples of all of said plurality of fluids are analyzedand then repeating the cycle.

12. In an apparatus for monitoring a fluid for the content of mercurypresent therein, wherein are provided:

(a) programming means for mechanically activating and deactivatingsuccessively and repetitively;

(b) means for removing from said fluid a sample of predetermined amountin a sample measuring zone;

(c) means for circulating aqueous hydrazine reagent cyclically from areagent storage zone through a reagent valve and through a reagentmeasuring zone and return to said reagent storage zone;

((1) means for removing from said circulating hydrazine reagent apredetermined amount of said hydrazine reagent and for transferring saidamount of hydrazine to said scrubbing zone;

(e) means for scrubbing the mixture in said scrubbing zone with agaseous carrier;

(f) means for separating said gaseous carrier containing mercury vaporfrom the resulting aqueous liquid in said scrubbing zone;

M (g) means for transferring said carrier containing mercury vapor to apyrolyzing zone to remove interfering materials from said gaseouscarrier; (h) means for transferring the resulting purified gase- 5 ouscarrier containing mercury vapor to a measuring zone;

(i) photometric means for measuring the quantity of mercury in saidcarrier;

(j) means for indicating the quantity of mercury in said carrierrelative to the predetermined amount of said sample;

the improvement which comprises:

(1) a storage zone for acidic metal salt reagent containing dissolvedoxidant,

(2) means for transferring a predetermined amount of said acidic metalsalt reagent containing dissolved oxidant from said storage zonetherefor to said sample measuring zone to form a mixture with said fluidsample; and

(3) means for transferring said mixture from said sample measuring zoneto a scrubbing zone.

13. The apparatus of claim 12 further including means for admixing andproportioning gaseous carrier with said predetermined amount of aqueoushydrazine reagent and for transferring the resulting mixture of saidaqueous hydrazine reagent and said gaseous carrier to said scrubbingzone.

14. The apparatus of claim 13 which additionally incorporates means forrecording the quantity of mercury in said carrier relative to thepredetermined amount of said sample.

References Cited UNITED STATES PATENTS 3,704,097 11/1972 Capuano 23-253R R. E. SERWIN, Primary Examiner 11.8. C1. X.R.

23---230 PC, 253 R, 253 PC

